ARRS 2022 Abstracts

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E1420. The Most Common Artifacts at Musculoskeletal Shear Wave Elastography and How to Avoid Them
Authors
  1. Carla Rodriguez; SRITE Radiologia
  2. Ivan Gomez; Hospital de Kennedy
Objective:
Shear wave elastography (SWE) is a fairly well-established quantitative method of assessing tissue elasticity or stiffness and has shown promising results in the musculoskeletal system. In contrast to strain imaging, SWE provides quantitative measurements. The main advantages of Acoustic Radiation Force Impulse (ARFI) imaging have been reported, although several technical limitations exist and artifacts are common. This exhibit aims to describe the most common artifacts seen in musculoskeletal tissues using ARFI SWE; recognize the presence and types of artifacts at musculoskeletal tissues with the use of ARFI SWE; identify several artifacts that frequently accompany musculoskeletal pathologies; and revise the techniques in order to avoid those artifacts. SWE is used for the assessment of the mechanical properties of tissues, including the muscle and tendons. ARFI imaging increases diagnostic performance when coupled to conventional ultrasound. It is important to recognize, minimize, and, when possible, eliminate US artifacts that can lead to erroneous interpretation of musculoskeletal tissues.

Materials and Methods:
ARFI is a focused acoustic beam generated by the US transducer to compress the underlying tissue, thereby inducing a local shear wave. The speed of that wave or the shear wave velocity (SWV), is then measured as it propagates through the tissue and displayed as a parametric image or through selective region-of-interest (ROI) analysis, measured in m/per second. SWV provides a quantitative metric of tissue stiffness because it directly relates to the local shear elastic modulus, such that the stiffer the tissue, the greater the SWV. Consequently, some vendors directly display shear wave data as elastic modulus in kilopascals or meters/seconds.The application of ARFI was performed using a S2000 Siemens system with 18L6 linear probe with a total of 50 healthy volunteers, randomly selected between 18 to 55 years old (24 female, 26 male) without tendon pathology history. Both the patellar and Achilles tendon were evaluated.

Results:
The most common artifacts are shown, due mostly to the transducer use. SWE artifacts include transducer pressure, tendon position, tissue interfaces, tissue composition (viscoelasticity), software related and scale use. Technical issues and lack of standardization limits SWE ARFI use in the assessment of tendon and muscle injury.

Conclusion:
Artifacts are common in elastography images. Operator (compression) and software errors were the most common type of artifacts. As new techniques are developed, identification and avoidance of artifacts will expand as these methods, particularly SWE, are used more in clinical settings. It is important for the radiologist to be able to recognize and understand how to minimize or eliminate artifacts that can occur at SWE ARFI acquisition when musculoskeletal tissues are evaluated. The development of application-specific algorithms, standardization of imaging protocols, and calibration standards for SWE systems are strongly required.